1. Field of the Invention
The present invention relates to an image forming apparatus with an intermediate tray, such as a copier. More particularly, the invention relates to a copier possessing an intermediate tray for making two-sided copies or synthetic copies, and also possessing a sorter or other post-processing device.
2. Description of the Related Art
Hitherto, in a copier provided with a sorter, when making a two-sided copy from a first document (manuscript), the images are formed sequentially on the face side of a paper in the number of copies required, and the copies then are stocked on an intermediate tray. Then the document is inverted, and the sheets of paper copied on one side are taken out one by one from the intermediate tray, and images are sequentially formed on the reverse side. The sheets are sent into the sorter and sorted, while the next document is set on the contact glass at the same time, in order for the image forming apparatus to operate at high speed. The images are formed from the second document in the same manner as in the case of the first document.
Incidentally, in the high speed copier for copying the next document while sorting with the sorter, when the sheets being sorted by the sorter are jammed, the copied sheets of the next document already may be moving toward the intermediate tray, after the copying on one side of the copy paper is finished.
In such a case, if the copied sheets of the next document are sent directly into the intermediate tray, it is necessary to remove the jammed paper, set the initial document again on the contact glass, and copy it. Therefore, the copied paper of the next document and the copied paper of the initial document coexist in the intermediate tray, and the subsequent copy procedure is difficult.
To avoid this problem, in known apparatuses, if jamming occurs in the sorter, the entire apparatus is stopped, assuming that the jamming has occurred at the copier main body, whether the copy paper of the next document is jammed or not.
In such a conventional method, however, if the sorter is jammed, the copier main body is also considered to be jammed, although it is not actually jammed, and a jam clearing operation is needed at two positions, which takes time and labor.